Slope Stability Of Embankments Research Articles

Numerical investigation on factors for deep-seated slope stability of stone column-supported embankments over soft clay

Stone columns have been commonly used as an alternative to solve deep-seated slope stability problems. Due to the complexity of a three-dimensional (3-D) arrangement of multiple columns, a 3-D problem has been commonly converted into a two-dimensional (2-D) model which has equivalent properties and dimensions, by the column-wall method and the equivalent area method. In this paper, two column-wall approaches based on matching either column geometry or column properties were compared and verified by 3-D numerical results in the stability evaluation of the stone column-supported embankment over soft soils. This study also investigated the 2-D numerical models using the column-wall method and the equivalent area method considering the factors of stress concentration, area replacement ratio, and soil conditions under short-term and long-term conditions. The numerical results show that the equivalent area method resulted in a continuous critical slip surface in the stone column-supported embankment over soft soil; however, no continuous slip surface developed using the column-wall method. Under the short-term condition, the computed factor of safety by the equivalent area model with or without considering the stress concentration effect was greater than that computed by the column-wall model. However, their difference became smaller under the long-term condition. The columns at certain locations along a prescribed slip surface from the equivalent area method did not mobilize their shear strengths under the short term condition. A reduction factor of 0.9 is suggested to correct the calculated factor of safety by the equivalent area method without considering the stress concentration ratio to that by the column-wall method under the short-term condition. No reduction factor (or the reduction factor of 1.0) is proposed under the long-term condition.

Numerical Simulation of the Stability of Added Lime Expansive Soils Embankment

The main reason of expansive soil embankment slope landslide is the infiltration of rainwater. Analyzing engineering characteristics and failure mechanism of expansive soil embankment slope, considering the force of expansion under the infiltration of rainwater, and choosing the appropriate constitutive model, simulate expansive soil embankment slope under humidification state. According different conditions of the expansive soil and different depth of infiltration, and simplifying the swelling force, establish a simple and reasonable model of expansion force changes. Expansive soil embankment slope stability is mainly affected by the moisture of expansive soil slope after analyzing the calculation results. The safety of expansive soil slope after immersion in rainwater decreases significantly. It shows designers should choose reasonable slope ratio and consider the embankment slope protection and drainage measures.

Seismic stability evaluation of embankment slope based on catastrophe theory

An evaluation method for the seismic stability of embankment slope was presented based on catastrophe theory. Seven control factors, including internal frictional angle, cohesion force, slope height, slope angle, surface gradients, peak acceleration, and distance to fault were selected for analysis of multi-level objective decomposition. According to the normalization formula and the fuzzy subject function produced by combination of catastrophe theory and fuzzy math, a recursive calculation was carried out to obtain a catastrophic affiliated functional value, which can be used to evaluate the seismic stability of embankment slope. Fifteen samples were used to verify the effectiveness of this method. The results show that compared with the traditional quantitative method, the catastrophe progression owns higher accuracy and good application potential in predicting the seismic stability of embankment slope.

Sand Soil Properties as the Sea Embankment Material Used in Pipe-Bag Riding Method

Comparing with the stability demands of construction material used in pipe-bag riding technology for sea embankments, and based on many site and laboratory tests of sand distributed in Dongtai offshore, Northern Jiangsu Province in China for reclamation engineering, the type of sand, mechanical composition, grain shape, coefficient of permeability and liquefaction potential of sands were discussed. Additionally, the sea embankment slope stability analysis and seepage stability analysis demonstrate the sands can be used in sea embankment construction for pipe bag method

The Analysis of Seepage Characteristics and Stability of Carbonaceous Mudstone Embankment Slope in Rainfall Condition

Based on the actual rainfall data and saturated-unsaturated seepage theory, the change of pore water pressure and volumetric moisture content of carbonaceous mudstone embankment slope were studied under designed rainfall intensity. At the same time, the effect of rainfall intensity change on the slope failure mode and safety coefficient was analyzed. The results of the study show that: Continuous rainfall will make the surface layer negative pore water pressure of carbonaceous mudstone embankment slope loss, and in transient saturation zone the volumetric moisture content reaches the saturated moisture content. Safety coefficient of carbonaceous mudstone embankment slope gradually decreases with the rainfall continuing, potential sliding surface also have the tendency of extending into the embankment.

The Analysis of Seepage Characteristics and Stability of Carbonaceous Mudstone Embankment Slope in Rainfall Condition

Based on the actual rainfall data and saturated-unsaturated seepage theory, the change of pore water pressure and volumetric moisture content of carbonaceous mudstone embankment slope were studied under designed rainfall intensity. At the same time, the effect of rainfall intensity change on the slope failure mode and safety coefficient was analyzed. The results of the study show that: Continuous rainfall will make the surface layer negative pore water pressure of carbonaceous mudstone embankment slope loss, and in transient saturation zone the volumetric moisture content reaches the saturated moisture content. Safety coefficient of carbonaceous mudstone embankment slope gradually decreases with the rainfall continuing, potential sliding surface also have the tendency of extending into the embankment.

Study on Scouring Stability of Powder Sand Embankment Slope with Cover Layer

Abstract. The content of clay particles in powder sand is low, with small cohesion. Embankment erosion by water will lead to instability, to make a cover layer with clay. In order to resolve the erosion of powder sand embankment slopes affected by the rain, tested the powder sand and the cover layer soil, and conducted a survey of slope erosion situation in the embankment, divided the types of erosion. On this basis, base on the energy method, analysis the slope erosion by the impact of slope gradient, slope shape, the density and width of cover layer soil, rainfall intensity, conclude some applicable scouring protective measures for conditions of slope. The results provide a reference for the design of powder sand slope protective technology.

Seismic Slope Stability of Embankments Constructed with Pond Ash

Utilization of pond ash in large earthworks for geotechnical applications like construction of highway embankments, raising of ash dykes and filling low lying areas (construction fills), solves the waste disposal problem besides conserving the natural soils. However, design and construction of such geotechnical structures particularly in earthquake prone areas, requires thorough understanding of dynamic response of these structures under different seismic loading conditions. Here in this article, dynamic stability of embankments raised around the perimeter of ash ponds by the upstream and down stream methods of construction with coarse (ash from inflow point) and fine (ash from outflow point) pond ash materials, has been computed for different site specific earthquake scenarios appropriate for Delhi region. The performance of the embankments is analyzed using Quake/w and Slope/w software packages for steady-state seepage condition. The required dynamic properties of the materials are obtained form the various field and laboratory tests. The geotechnical structures constructed with ash exhibited similar type of response as that of with the natural soils. The performance of the structures is influenced by number factors such as type of construction (e.g. upstream or downstream), insitu conditions (e.g. stresses, density, phreatic line), and magnitude of dynamic loads, besides on the static and dynamic characteristics of the materials. The structures with the fine ash exhibit higher vulnerability to liquefaction related failures, which emphasizes need for carrying site-specific studies and adoption of proper construction measures to ensure design parameters.

Assignment of safety criteria to the stability of earthen slopes of retaining structures

The problem of determining criterial values of K1 and K2 is examined for the enclosing dike of an intake channel as a function of the position of the depression curve and a seismic effect. The requirements of regulatory documents are analyzed. Suggestions are made for determination of the criterial value of K2 with respect to the slope stability of artificial embankments.

An Analysis of Slope Stability of Sand Embankment with Shear Strength Reduction (SSR) Method

Comparing with conventional expressway embankment filled with clay only, the sand embankment tipped by intensely-weathered rock (IWR) can effectively reduce the consumption of cultivated land resource caused by the construction of expressway engineering. So it is significant to research the constructions of sand embankment tipped by IWR if local sand resources are enough. Combined with the construction of Qing-Lin freeway, in China, the slope stability of the embankment filled with sand and tipped by IWR outside was analyzed in the paper, and the analysis was conducted by the strength reduction method. The effects of the changes of compaction, water content, ratio of slope, height of the embankment and different IWR-width on the safety factor of the slope stability were investigated. The results indicate that, when the height of embankment is constant, the ratio of slope is the most important factor which influences the stability of side slope, and the IWR-width does not have a decisive effect on the safety factor on subsoil condition and it can be determined according to the convenience of site construction.

Numerical Modeling of Geofoam Embankments

In 2001, the Utah Department of Transportation completed a 4-year $1.4 billion I-15 reconstruction project in Salt Lake City, Utah. This project included widespread use of expanded polystyrene geofoam as lightweight embankment at important utility crossings and where close proximity to existing buildings necessitated minimizing consolidation settlement. This paper presents construction and long-term monitoring results for some of these embankments with numerical modeling of the field measurements. Fast Lagrangian Analysis of Continua, a finite-difference program, was used to estimate the complex stress distribution and the displacements (i.e., strain) that developed in select geofoam embankments. The writers used a bilinear elastic model to produce reasonable estimates of gap closure, block seating, and the subsequent elastic compression of the geofoam embankment at higher stress levels. Such estimations are important for modeling and designing geofoam embankments and potential connections with other systems. The calculation of the complex stress distribution and displacements that develops in a geofoam embankment has application to settlement, lateral earth pressure against retaining and buried walls, slope stability, and seismic design of geofoam embankments.

Evaluation of waste embankment slope stability: Valea Manastirii, Gorj, Romania

One of the largest mining waste deposits in Romania is in the Montru valley where coal has been exploited for many years. The waste embankment is 60 m high and covers an area of 6 km2 . In March 2000 a large landslip occurred with lateral movement in the order of 30 to 50 m which resulted in the blocking of the River Montru. The slip surface extended downwards into the Pliocene deposits beneath the river floor. The paper describes the investigations undertaken to assess the short and long term stabilty of the waste embankment.

Swelling pressure of sodium montmorillonites

Determination of the swelling pressure of montmorillonitic clays is required in many situations concerned with stability problems of foundations, retaining walls, slope stability of embankments and excavations in expansive soils. Recently expansive soils such as bentonite have been used as a mixture backfill material, for example as backfill material for nuclear waste disposal systems, for which a knowledge of the swelling pressure is desirable. This is the pressure required to keep the clay-water system at the required void ratio when it is allowed to absorb water or electrolyte. If the pressure is less than the swelling pressure, volume expansion occurs; if the pressure is more than the swelling pressure, volume compression occurs. Because of isomorphous substitutions in the crystal lattice, in general the clay particles carry negative charges at the surfaces of the platelets. Exchangeable cations in the clay media are attracted to these negative charges, but this attraction is opposed by the tendency of ions to be distributed. As a result, an electric diffuse double layer is formed (Gouy, 1910).

DEFORMATION BEHAVIOR AND STABILITY OF HIGH EMBANKMENT SLOPE CONSTRUCTED AT STEEP-VALLEY (RIVER TERRACE DISTRICT)

DEFORMATION BEHAVIOR AND STABILITY OF HIGH EMBANKMENT SLOPE CONSTRUCTED AT STEEP-VALLEY (RIVER TERRACE DISTRICT)

Filtration through hydraulic embankments made of colliery spoil: model tests

Model embankments made of colliery spoil and fuel ash were investigated in a hydraulic channel. Seven models of colliery spoil with or without additional sealing elements from the ash, as well as one of ash itself, were constructed. The effect of granulometric composition, compaction, different types of sealings, and the silting-up process on embankment perme ability was ascertained. Embankment slope stability was also analysed with respect to seepage pressure and strength param eters of the slope material. The effect of granulometric com position, thickness of sealing elements, and silting-up on water seepage through the embankments was significant. On the other hand, compaction had less influence than the above mentioned factors. The effect of seepage pressure on slope stability of the embankment made from fuel ash was failure. General recommendations for building hydraulic earth structures using the materials investigated are pre sented.

Influence of Particle Breakage on the Stability of Embankment Slope

Influence of Particle Breakage on the Stability of Embankment Slope

Slope stability of embankments and excavations : Ambroz, J Proc 6th International Congress International Association of Engineering Geology, Amsterdam, 6–10 August 1990V3, P2075–2080. Publ Rotterdam: A A Balkema, 1990

Slope stability of embankments and excavations : Ambroz, J Proc 6th International Congress International Association of Engineering Geology, Amsterdam, 6–10 August 1990V3, P2075–2080. Publ Rotterdam: A A Balkema, 1990

Development in wedge shear testing of unsaturated clays and gravels : Geotechnique V41, N1, March 1991, P79–100

Means for measuring the shear strength at large strains in the wedge shear test over about the same range of normal stresses as at peak strength are described. By the same means it is now possible to prolong the test for larger shear displacements when loading is near-vertical; to perform a re-shear test on cut planes; to obtain a strength envelope using a single test mould; and to perform a multi-stage shear teat if desired. A double-cut, cylindrical teat mould is described which enables clays or fine gravels to be sheared, in the same moulds in which they have been compacted, along planes relevant to the slope stability of embankments. A sufficiently accurate shear strength envelope can be obtained from two such cylindrical wedge shear tests (cylwests) which can be performed within 1 h. A larger version of this set-up, using a portable frame and a prismatic box cut to provide a shear plane area of 9OO cm2 as in the in situ wedge shear teat (iswest), is also described. This version (priswest) has been us...

Development in wedge shear testing of unsaturated clays and gravels

Means for measuring the shear strength at large strains in the wedge shear test over about the same range of normal stresses as at peak strength are described. By the same means it is now possible to prolong the test for larger shear displacements when loading is near-vertical; to perform a re-shear test on cut planes; to obtain a strength envelope using a single test mould; and to perform a multi-stage shear teat if desired. A double-cut, cylindrical teat mould is described which enables clays or fine gravels to be sheared, in the same moulds in which they have been compacted, along planes relevant to the slope stability of embankments. A sufficiently accurate shear strength envelope can be obtained from two such cylindrical wedge shear tests (cylwests) which can be performed within 1 h. A larger version of this set-up, using a portable frame and a prismatic box cut to provide a shear plane area of 9OO cm2 as in the in situ wedge shear teat (iswest), is also described. This version (priswest) has been us...

Probabilistic approach for embankment slope stability analysis : Goel, M C; Muhasyim Proc ninth regional conference for Africa on soil mechanics and foundation engineering, Lagos, September 1987V1, P387–394. Publ Rotterdam: A A Balkema, 1987

Probabilistic approach for embankment slope stability analysis : Goel, M C; Muhasyim Proc ninth regional conference for Africa on soil mechanics and foundation engineering, Lagos, September 1987V1, P387–394. Publ Rotterdam: A A Balkema, 1987